1. Technical Field of the Invention
This invention relates to an attachment apparatus for a disc protective sheet, which is adapted for attaching, to halves constituting a cartridge body, a disc protective sheet attached on the surface opposite to the disc of the cartridge body within which the disc is rotatably accommodated, the protective sheet being adapted to sweep foreign materials such as dust, etc. attached to the disc to thereby protect the disc, and an attachment method therefor.
2. Description of the Related Art
Hitherto, in a disc cartridge for rotatably accommodating a magnetic disc within a cartridge body, in order to prevent the magnetic disc from being polluted by dust admitted into the cartridge body, a disc protective sheet is attached on the surface opposite to the magnetic disc of the cartridge body. This disc protective sheet is formed by punching unwoven cloth in the state where it has an outer shape slightly larger than an outer shape of the magnetic disc, and is substantially circular.
In the assembly process steps of the disc cartridge, such disc protective sheets are respectively attached, by an attachment apparatus for a disc protective sheet, on surfaces opposite to the magnetic disc of the upper and lower halves constituting a cartridge body. This attachment apparatus includes a supply mechanism for supplying disc protective sheets onto the inner surfaces of the upper and lower halves carried by a conveyer, etc., and a fixing mechanism for fixing the disc protective sheets at the periphery of recording/reproduction opening portions of the inner surfaces of the upper and lower halves. The fixing mechanism includes a head portion for pressing the disc protective sheets onto the inner surfaces of the upper and lower halves, wherein plural pressing pieces for pressing the disc protective sheet are formed in a saw-tooth form in a manner perpendicular to the pressing surface onto the pressing surfaces for pressing the disc protective sheets of this head portion. These pressing pieces are formed so as to have the ability to press the disc protective sheet onto the peripheral edge portion of the recording/reproduction opening portion. In addition, a heating portion for heating the head portion is provided at the fixing mechanism.
In such an attachment mechanism, when disc protective sheets are delivered to the internal surfaces of the upper and lower halves by the supply mechanism, the disc protective sheets are fixedly fused at peripheries of the recording/reproduction opening portions of the internal surfaces of the upper and lower halves by a fixing mechanism. Specifically, the fixing mechanism presses the head portion heated by the heating portion onto the disc protective sheet. Because saw-tooth shaped pressing pieces are heated by the heating portion, the head portion bites the disc protective sheets into the periphery of the recording/reproduction opening portions of inner surfaces of the upper and lower halves so that they are fixed.
In such an attachment apparatus for disc protective sheet, since the disc protective sheets are fixedly fused at peripheries of the recording/reproduction opening portions of the upper and lower halves and are only attached thereat, the attachment state of other portions of the disc protective sheet becomes unstable, resulting in instances where dust attached on the magnetic disc cannot be completely swept. Particularly, in the case of the magnetic disc onto which information signals are recorded at high density, when dust attached to the magnetic disc cannot be swept, a recording/reproduction error may be apt to take place. Moreover, since such an attachment unit is adapted so that the fixing mechanism partially presses the peripheries of the recording/reproduction opening portion of the upper and lower halves, the upper and lower halves may be deformed. Further, since the disc protective sheets are adapted so that since the entire surfaces are not fixedly fused at the upper and lower halves, there are instances where the disc protective sheet may be bent within the cartridge body and the attachment position of the disc protective sheet deviates so that a portion of the disc protective sheet may be protruded toward the external from the recording/reproduction opening portion.
In view of the above, an object of this invention is to provide an attachment apparatus for a disc protective sheet and an attachment method therefor which can fixedly fuse the disc protective sheet onto the surface opposite to the disc half, and which can fixedly fuse, efficiently and reliably, the disc protective sheet onto the half constituting part of the cartridge body.
An attachment apparatus for a disc protective sheet according to this invention is an attachment apparatus for a disc protective sheet, wherein the disc protective sheet for protecting the disc is rotatably accommodated within the cartridge body formed by connecting a pair of upper and lower halves, and is attached on the surface opposite to the disc of at least one half. This apparatus includes a supporting mechanism having an outer shape slightly larger than the disc protective sheet and for supporting a half constituting a cartridge body to which a disc protective sheet is attached; a supply mechanism for supplying the disc protective sheet to the half, the disc protective sheet being such that a cut portion slightly larger than an opening portion is provided at the half and facing a portion of the disc to the external; a thermal fusible layer provided on an attachment surface with respect to the surface opposite to the disc of the half, wherein the thermal fusible layer is opposed to the surface opposite to the disc of the half and the cut portion is caused to correspond to the opening portion; and a fusing mechanism having an outer shape slightly larger than the disc protective sheet and disposed in a manner opposite to the supporting mechanism, the fusing mechanism serving to fuse the thermal fusible layer of the disc protective sheet fixedly to the half.
Since the supporting mechanism is moved to the fusing mechanism side so that the fusing mechanism and the supporting mechanism are relatively moved, the disc protective sheet delivered to the surface opposite to the disc of the half constituting the cartridge body is fixedly fused onto the surface opposite to the disc of the half, by the fusing mechanism, wherein the half is placed between the fusing mechanism and the supporting mechanism. The supporting mechanism includes a supporting member for supporting the half. This supporting member is formed by an elastic member and is adapted so that groove portions are formed at the supporting surface side for supporting the half. The supporting member having a supporting surface at which groove portions are formed is easily deformed in a manner to absorb distortion such as a warp of the half mounted on the supporting surface, etc., thereby making it possible to uniformly support the entire surface of the half. Thus, the disc protective sheet can be fixedly and securely fused onto the half.
Moreover, the engagement portion of the positioning mechanism for carrying out the positioning of the cartridge body, is engaged with the opening portion of the half. Further, in fixedly fusing the disc protective sheet onto the half, the half is pressed toward the supporting mechanism side by a pressing mechanism. The disc protective sheet is provisionally fixed or attached at the peripheral edge portion of the opening portion of the half by a provisional attachment or fixing mechanism before it is fixedly fused onto the half, thereby making it possible to securely fuse the attachment surface of the protective sheet at a predetermined position.
An attachment method for the disc protective sheet according to the invention is directed to a method for attaching, onto the surface opposite to the disc of at least either one half, the disc protective sheet for protecting the disc rotatably accommodated within the cartridge body formed by connecting a pair of upper and lower halves. The method includes a step of supplying the disc protective sheet to a half, the disc protective sheet being such that a cut portion, being relatively larger than that of an opening portion, is provided at the half, for facing a portion of the disc toward the external, and a thermal fusible layer is provided at the attachment surface with respect to the surface opposite to the disc of the half; wherein the thermal fusible layer is opposed to the surface opposite to the disc of the half and the cut portion is caused to come in correspondence with the opening portion, and wherein the fusing of the thermal fusible layer of the disc protective sheet delivered to the half is performed to fixedly fuse the disc protective sheet onto the half.
At the preceding step of fixedly fusing the disc protective sheet with respect to the half, a thermal fusible layer of a cut portion peripheral edge portion of the disc protective sheet which is delivered to the half, is fused. Thus, the disc protective sheet is fixedly fused onto the peripheral portion of the opening portion so that it is provisionally fixed or attached.
Still further objects of this invention and more practical merits obtained by this invention will become apparent from the description of the embodiments which will be given below.